1. Field of the Invention
The present invention relates to an adapter-type endoscope that includes light-emitting devices in a distal end adapter as an illumination optical system of an endoscope, in which the distal end adapter can be exchangeably mounted to an insertion portion.
2. Description of the Related Art
Since the examination target of an endoscope is the inside of a living body or a pipe at a plant or the like, an endoscope requires a light source that illuminates the examination target. In a common endoscope apparatus, a light source device is prepared as an external apparatus of the endoscope. The illumination light emitted by the light source device is supplied to a light guide provided in the endoscope.
In recent years, endoscopes are also being practically applied in which LED illuminations that are light-emitting devices are provided at a distal end portion of an insertion portion. Such endoscopes are configured to illuminate an examination target with the light emitted from the LED illuminations. In an endoscope that includes LED illuminations, an electric wire that supplies power is arranged inside the insertion portion instead of a light guide. Hence, it is possible to realize an endoscope with high functionality and a simple configuration that has an insertion portion with a small diameter.
However, in an endoscope that includes LED illuminations, there is the risk of problems occurring due to heat emitted from the LED illuminations. These problems include a decrease in the illumination light amount or an increase in the temperature of an image pickup device leading to the generation of image noise.
For example, Japanese Patent Application Laid-Open Publication No. 2004-248835 (hereunder, referred to as Document 1) discloses an endoscope that prevents problems including a decrease in the illumination light amount or generation of image noise due to heat emitted by LED illuminations installed at a distal end portion of an insertion portion, and can perform favorable observation over a long time.
This endoscope includes a bundled wire member as a heat releasing member. One end of the bundled wire member is installed in the vicinity of the LED illuminations. The other end of the bundled wire member is installed in a flexible tube portion included in the insertion portion. According to this configuration, since heat emitted from LED illuminations provided in the distal end portion is released by the bundled wire member, it is possible to prevent the LED illuminations from becoming a high temperature and prevent heat of the LED illuminations being conducted to the image pickup device.
In recent years, an adapter-type endoscope is also being practically applied in which a distal end adapter that includes light-emitting devices as an illumination optical system is exchangeably mounted to an insertion portion of an endoscope. With this adapter-type endoscope also, it is necessary to release heat generated from LED illuminations and the like provided in the distal end adapter. Therefore, the adapter-type endoscope is provided with a bundled wire member that is substantially the same as in the aforementioned Document 1 as shown in FIG. 1 to FIG. 5. Heat emitted by the LED illuminations is released by the bundled wire member to thereby prevent a problem whereby the amount of illumination light decreases or image noise is generated.
A configuration example of the conventional adapter-type endoscope will now be described referring to FIG. 1 to FIG. 5. FIG. 1 is a front view of an adapter-type endoscope. FIG. 2 is a cross section in the longitudinal direction of the adapter-type endoscope along a line II-II in FIG. 1. FIG. 3 is a cross section along a line III-III in FIG. 2. FIG. 4 is a cross section along a line IV-IV in FIG. 2. FIG. 5 is a cross section along a line V-V in FIG. 2.
As shown in FIG. 2, an adapter-type endoscope 100 includes a distal end adapter 110 and an insertion portion 130 to which the distal end adapter 110 is detachably mounted.
As shown in FIG. 1, FIG. 2, and FIG. 3, the distal end adapter 110 includes an adapter main body 111, an LED substrate 112, a cylinder 113, a detachable ring 114, an observation optical system 115, and a pair of adapter-side electrical connection portions 120 and the like. LED illuminations 118 are mounted on the LED substrate 112.
The adapter main body 111 is a receiving member for the LED illuminations 118, and conducts heat generated at the LED illuminations 118. As shown in FIG. 2 and FIG. 3, the adapter main body 111 includes a first through hole 116 and a pair of second through holes 117. The observation optical system 115 is installed in the first through hole 116. The adapter-side electrical connection portions 120 are installed in the second through holes 117, respectively.
The cylinder 113 is integrally fixed to the adapter main body 111 by, for example, two fixing screws 109 as shown in FIG. 3.
As shown in FIG. 2, the detachable ring 114 is rotatably mounted with respect to the adapter main body 111. The ring 114 includes a female screw portion 108 on the inner peripheral surface thereof.
The LED substrate 112 has, for example, a disk shape as shown in FIG. 1. The substrate 112 includes a conductive pattern (not shown) on one surface side. A plurality of LED illuminations 118 are mounted at predetermined positions on the conductive pattern. Further, contact pins 121 of the adapter-side electrical connection portions 120 are connected to the conductive pattern of the LED substrate 112. A central through-hole 119 for installing the observation optical system 115 is formed in the LED substrate 112.
As shown in FIG. 2, the adapter-side electrical connection portion 120 mainly includes the contact pins 121, an abutting pin 122, a case body 123, and an insulation cylinder 124. As shown in FIG. 3, a coil spring 125 is arranged inside the case body 123. The abutting pin 122 is configured to advance or retract with respect to the case body 123.
The contact pins 121, abutting pin 122, case body 123, and coil spring 125 are formed with a conductive member of aluminum, brass, iron, or the like.
As shown in FIG. 2, the insertion portion 130 includes a distal end portion 101, a bending portion 102, and a flexible tube portion (unshown) that are sequentially connected. For example, the distal end portion 101 includes a distal end portion main body 131, a first outer sheath portion 132, a second outer sheath portion 133, an image pickup optical system 134 having an image pickup device 103 and the like, and an endoscope-side electrical connection portion 104.
As shown in FIG. 2 and FIG. 4, the endoscope-side electrical connection portion 104 includes a cylindrically shaped electrode 105 and a tubular insulating portion 106. The distal end portion main body 131 is a receiving member that abuts against the adapter main body 111 and conducts heat that has been conducted to the adapter main body 111. A through hole 135 and a pair of stepped through-holes 136 are formed in the distal end portion main body 131. The image pickup optical system 134 is installed in the through hole 135. As shown in FIG. 4, a distal end surface of a fixing screw 107 is pressed against an image pickup frame 139 included in the image pickup optical system 134 to thereby integrally fix the image pickup optical system 134 to the distal end portion main body 131.
As shown in FIG. 2, the stepped through-hole 136 includes a large-diameter hole 137 and a small-diameter hole 138. The endoscope-side electrical connection portion 104 is fixedly arranged in the large-diameter hole 137. A power source wire 141 for supplying power to the LED illuminations 118 is inserted through the small-diameter hole 138.
The configuration is such that, by means of an urging force of the coil spring 125, the abutting pin 122 of the adapter-side electrical connection portion 120 abuts against a surface of the electrode 105 of the endoscope-side electrical connection portion 104 that is fixedly arranged in the large-diameter hole 137. A hole is formed in the other end of the electrode 105. A conducting wire 142 of the power source wire 141 is electrically connected inside the hole. The conducting wire 142 passes through the through hole of the insulating portion 106 to be installed inside the hole of the electrode 105.
One end of a bundled wire member 143 for releasing heat is connected to the distal end portion main body 131. As shown in FIG. 5, for example, four bundled wire members 143 extend from the distal end portion main body 131.
As shown in FIG. 2 and FIG. 5, the power source wires 141 and the bundled wire members 143 are inserted through the inside of the bending portion 102 from the distal end portion main body 131 and extend in the direction of the flexible tube portion. Reference numeral 145 denotes a signal wire that extends from the image pickup optical system 134. Reference numerals 146 denote bending wires.
According to the adapter-type endoscope 100 configured as described above, heat generated at the LED illuminations 118 is conducted to the adapter main body 111 via the LED substrate 112. The heat conducted to the adapter main body 111 is subsequently conducted to the distal end portion main body 131 of the insertion portion 130, and thereafter conducted to the bundled wire members 143 extending from the distal end portion main body 131. The heat is released inside the insertion portion 130 and the like to thereby prevent occurrence of a problem due to a rise in temperature.
However, with respect to adapter-type endoscopes also, users desire that the insertion portion is provided with a small diameter. In the case of an adapter-type endoscope, when the diameter of the insertion portion is made smaller, the outer dimensions of the adapter main body that conducts heat and the outer dimensions of the distal end portion main body also become smaller. Hence it is difficult to secure space for providing bundled wire members.